My interest in this topic grew as I was researching anti-aging, and Josiah Zayner at The Odin released his IGF-1 Gene Therapy with Frog Kit. The kit gene modified IGF-1 in the frogs making them substantially more muscular.

By Philip CohenBIGGER, stronger muscles can be produced by gene therapy, an experiment on mice suggests. Loss of muscle mass can cripple and kill patients with conditions such as muscular dystrophy. And even ordinary ageing saps up to one third of our strength. “Slowing down that process could mean the difference between someone being mobile […]

Comment Update

By Philip CohenBIGGER, stronger muscles can be produced by gene therapy, an experiment on mice suggests. Loss of muscle mass can cripple and kill patients with conditions such as muscular dystrophy. And even ordinary ageing saps up to one third of our strength. “Slowing down that process could mean the difference between someone being mobile […]

Adeno-Associated Virus (AAV) as a Vector for Gene Therapy

AAV was discovered over 50 years ago and has since become one of the leading gene delivery vectors in clinical development. As a result of its unique biology, simple structure, and no known disease associations, AAV could become the vector of choice for most gene therapy applications. Gene therapy using rAAV has been demonstrated to be safe and well-tolerated in virtually every clinical setting in which it has been used. These studies, along with basic research on its biology, have revealed many facets of this vector that can be applied to future efforts.

In order to be effective, gene therapy must satisfy four major parameters: the vectors has to be able to carry the target gene, has to be cheaply produced in large quantity, has to produce low immune-response and has to be stable expressed. Using such approaches we determined that the capacity of the mIGF-1 transgene to attenuate the structural and functional consequences of muscle aging was independent of its action during embryogenesis or early postnatal life.

Introduction of mIGF-1 somatically using an AdenoAssociated-Viral (AAV) vector was sufficient to rejuvenate the leg muscles of 27 month old mice, which exhibited the same mechanical force as legs of younger mice, and did not develop the pathological characteristics of senescent muscle [3]. The dramatic hypertrophy induced by expression of virally delivered IGF-1 is the consequence of a combination of satellite cell activation and an increase of protein synthesis [3, 4].

In addition, age-related reduction in force production and loss of fast fibers, all of which are typical of ageing skeletal muscle, were prevented both by virally delivered IGF-1 gene expression [3]. Understanding the signal transduction pathways involved in muscle wasting will help to devise therapeutic strategies to combat muscle degeneration.

Blocking proteolytic pathways or inducing muscle regeneration with pharmacological intervention will require a detailed knowledge of the signalling mechanisms involved, and the extent to which blocking or enhancing these pathways will be detrimental to other physiological parameters such as motor innervation.

Optimizing IGF-I for skeletal muscle therapeutics

We propose that long-term IGF-I expression results in IGF-I–driven enhancement of the repair mechanisms that direct satellite cell activation, proliferation, and differentiation so that fiber degeneration does not go unchecked.

IGF-I is a potent signal for growth in a number of tissues. Limiting its expression to muscle by driving it with a fast muscle-specific promoter and using an isoform that does not enter the circulation enables skeletal muscle to be the sole target of IGF-I activity (Musaro et al., 2001). However, because skeletal muscle is comprised of multiple cell types, IGF-I secreted from muscle fibers could stimulate other cells in addition to muscle fibers and satellite cells. Fibroblasts, in particular, are responsive to IGF-I (Petley et al., 1999) and are the source of the increased collagen deposition seen in dystrophic muscles. In the transgenic mouse that overexpresses human IGF-I, fibrosis was observed in the heart in animals over 1 yr of age (Delaughter et al., 1999), confirming the possibility that in our model, IGF-I would drive fibrosis as well. Even though IGF-I has been shown to stimulate fibroblasts, there is a net decrease in fibrosis in diaphragms of the mdx:mIgf +/+ mice. In fact, age-related fibrosis in the mdx diaphragm was effectively eliminated by IGF-I expression (Figs. 6 and and7).7). It may be that the efficient and rapid repair of the mdx:mIgf +/+ muscles prevents the establishment of an environment into which the fibroblasts migrate. This is of particular relevance to the human dystrophic condition where virtually all skeletal muscles succumb to fibrosis (Louboutin et al., 1993; Morrison et al., 2000). Thus, the results found in the mouse diaphragm suggest that IGF-I might be effective not only in increasing muscle mass and strength, but also in reducing fibrosis associated with the disease.

The effect of IGF-I on other tissues might also contribute to the preservation of fiber type in the older animals. When muscle fibers are severely damaged and lose innervation, it has been shown that slow motor neurons are more apt to reinnervate the regenerated fibers (Desypris and Parry, 1990). Given that neurons also respond to IGF-I, it is possible that the difference in reinnervation properties is minimized in these animals. Alternatively, the muscle repair mechanisms, which are enhanced by the presence of IGF-I (Musaro et al., 2001), might aid in muscle repair without the occurrence of degeneration. Although we have not directly tested these possibilities, the lower degree of myonecrosis apparent in mdx:mIgf +/+ muscle shows that there is less degeneration, and so perhaps less denervation. However, this observation does not exclude the potential effect on motor neurons.

On the basis of this overview of the literature, numerous potential explanations can be offered for the apparent lack of consistency between the rodent models and humans with regard to the role of GH/IGF-1 signaling in regulation of life span. The picture that emerges is of a complex endocrine/paracrine regulatory network that has effects on tissue and organ development as well as tissue function and energy homeostasis throughout life.

The general consensus is that in the postdevelopmental stage of life, GH and IGF-1 have numerous beneficial/protective actions in skeletal muscle and the cardiovascular and nervous systems but nevertheless increase insulin insensitivity and cancer risk. Based on these studies, it would be expected that these hormones have differential effects on health-span and life-span based, in part, on the age-specific tissue dysfunction and pathologies evident for each species and strain.

Taken together, the perceived contradictory roles of GH and IGF-1 in the genesis of the aging phenotype should not be interpreted as a controversy on whether GH or IGF-1 increases or decreases life span but rather as an opportunity to explore the complex roles of these hormones during specific stages of the life span. Assessment of the mechanisms of these hormones during each stage of the life span and elucidation of the mechanisms by which GH and IGF-1 modulate pathways involved in life span regulation initiated during development will be essential in advancing research into the mechanisms of aging.

Delivery of AAV-IGF-1 to the CNS Extends Survival in ALS Mice Through Modification of Aberrant Glial Cell Activity

Specifically, we showed that injecting a recombinant AAV vector encoding IGF-1 within the DCN of SOD1G93A mice resulted in axonal transport of vector and/or expressed IGF-1 protein to the brain stem and all segments of the spinal cord. This, in turn, led to improved muscle function and a significant extension of life span. Furthermore, IGF-1 also attenuated astrogliosis, microglial activation, peroxynitrite formation, and glial cell–mediated release of TNF-α and NO

In this work we describe the functional and structural ef- fects of IGF-I gene delivery into multiple muscles of adult animals, using AAV vectors. At least three novel features render this mouse model relevant for both gene therapy and gene doping. First, unlike in previous models, we transduced all the major muscle masses of the four limbs, therefore being able to assess not only the strength of a single muscle but the overall performance of the mouse in a novel endurance test. Second, in the same animals we analyzed biochemical, functional, and structural parameters, thereby providing a complete scenario of the muscle response to IGF-I gene transfer over time. Third, to our knowledge, this is the first report of whole-proteome changes occurring in muscle on IGF-I gene transfer over time.

We found that the administration of AAV2-IGF1 to skel- etal muscle resulted in a relevant amount of muscle fibers displaying a central nucleus, suggesting an ongoing process of muscle growth, a moderate angiogenic response, and a switch of fiber type composition toward the slow type.

When the IGF-I-dosed mice were challenged by subjecting them to an exhaustive swimming test, the observed histo- logical and metabolic events were found to eventually result in markedly improved endurance, allowing the mice to swim for a 3-fold longer time than controls. Consistent with pre- vious results showing that IGF-I transgenic mice displayed an enhanced tetanic force (Musaro et al., 2001), this finding clearly shows that diffuse AAV2-IGF1 delivery to both fore- limbs and hind limbs confers not only a specific gain in muscle power, but also higher endurance in a complex physical activity such as swimming. Thus, our model fully supports the concept that IGF-I gene delivery can be consid- ered a realistic way to achieve greater athletic performance.

Comment Update

What is IGF-1? IGF-1 Explained

IGF-1 is short for Insulin-like growth factor 1. It is a protein that is made from the IGF1 gene. It is a hormone with a critical role in tissue growth and muscle growth in adults.

It is produced by the liver as a hormone. IGF-1 is manufactured in the body for life. It is one of the primary effects resulting from the release of Growth Hormone in the body to which is made in the anterior pituitary gland.

IGF-1 is capable of stimulating growth on almost every cell in the body. It has prominent effects on increasing growth of skeletal muscle which is the reason it is of prime interest to researchers and doctors.

It works by binding to at the very least two cell surface receptor tyrosine kinases, both the IGF-1 receptor (IGF1R) and the insulin receptor. This works partly by activating the AKT signaling pathway, which both stimulates cell growth AND INHIBITS programmed cell death (important for aging and cancer concerns). Full details of all the mechanisms and signal pathways are too detailed to cover here.

IGF-1 only activates the insulin receptor at 0.1x the potency of actual insulin.

IGF-2 is closely related to IGF-1 but receptor lacks signal transduction capability, and mainly acts as a "sink" so less IGF-2 binds to IGF-1 receptors.

The IGF-1 pathway is a majorly linked to biological aging in many organisms, however, the exact effect of extra exogenous IGF-1 is not entirely clear, especially on mammals.

IGF-1 is banned by major sporting associations due to its potential use as a doping agent.

Comment Update

Why is it a Target for Gene Therapy? What are the Benefits?

There are several reasons why scientists think IGF-1 has great potential as a target for gene therapy both in anti-aging, and disease treatment, and for some biohacking enthusiasts - human augmentation and enhancement.

Losing muscle happens naturally with aging, but people with conditions like muscular dystrophy, it can cripple and be lethal. At least one third of our strength is lost via just natural aging. "Slowing down that process could mean the difference between someone being mobile and being helpless" says Lee Sweeney, a physiologist at the University of Pennsylvania in Philadelphia.

General aging via loss of muscle also eventually creates many problems for elderly people, such as the risk of slipping and falling, lost of balance and general physical weakness. Falling often leads to broken hips and other spiraling problems that come from physical injury, as such targeting IGF-1 for people may prevent such problems that arise from aging.

IGF-1 can be injected, but that's highly inefficient, especially for people who don't want to mess with needles daily, not to mention the cost and difficulty of buying such a thing in the first place.

Gene therapy allows the body to produce extra IGF-1 on its own and indefinitely, replacing the need for daily injections.

In general skeletal muscle make up a large part of daily living, everything we do from standing to eating requires the use of healthy and effective muscles. Disease and aging both affect the amount of IGF-1 we produce.

Potential complications with gene therapy would be much more permanent versus transient supplementation by intravenous injection, which is why a huge amount of research and safety testing is required before widespread mainstream release.

On top of this, IGF-1 can be used for doping in sports, which greatly limits its legality as it would bypass any kind of urine test currently used for sports people.

Comment Update

What is the Mechanism of Action for Gene Therapy?

The therapy in experimental tests such as Josiah Zayner's frog kit, currently works by injecting DNA into the limbs of the animal. According to The Odin's page, they use a special technique that isn't in common research use yet.

The frogs were given 50ug DNA injections of CMV-Human IGF-1 plasmid mixed with amphipathic polymers purchased commercially for in vivo transfection.

The DNA is mixed with a formulation that helps the cell uptake the DNA and use it if it were part of the cells DNA, over a period of days to weeks the DNA becomes unusable inside the cell and its function fades. This method is advantageous over viruses because it is much less immunogenic, costs less and easier to produce. Unlike CRISPR, this method doesn't directly edit the cells's DNA, making the effects non-permanent.

This innovative use of gene therapy is cutting-edge and not well known at this point in time.

Classic Viral Gene Therapy:

The virus is loaded with the gene that you want to insert, in this case a gene for IGF-1. The gene using the virus as a mechanism of transport, is transplanted into the cell, and the cell starts producing more IGF-1 (the hormone).

The specific virus used for IGF-1 gene therapy (also can be called gene doping) in experiments currently is the AAV. Together with IGF-1 it is called AAV-IGF-1.

AAV stands for Adeno Associated Virus. It delivers the gene to cDNA. AAV is a tiny virus that infects humans and cause little problems. AAV merges with the host's genome making it ideal for gene therapy vectors.

It will embed itself in a safe site in a stable manner in human chromosome 19. This makes the virus vector predictable, advances in AAV gene therapy have also lowered the probability of it being inserts into random places in the genome.

AAV does have some disadvantages. The cloning ability of the vector is limited. Larger genes cannot fit into the standard AAV vector, the virus has a 4.8 kilobase genome.

Comment Update

Research on Systematic Delivery of Recombinant IGF-1

The most straightforward but admittedly high maintenance way of increasing IGF-1 levels is to directly administrate it systematically. Several clinical trials have measured the efficacy of systemic delivery of recombinant IGF-1 in people who can benefit from increasing muscle growth and regenerative capacity.

IGF-1 has generally been used in limited amounts, due to the potential risk factor for cancer. Thus safety of higher dosages have not been established, however, data for the aging population and people suffering from ALS and myotonic dystrophy is sufficient as shown above.

Comment Update

Does Raising IGF-1 Accelerate Aging? Potential Risks of IGF-1 Therapy

Whilst increasing and maintaining muscle mass is good, there is established evidence that excessive anabolic activity accelerates aging. At what point does anabolic activity become undesirable?

As with HGH and other growth factors, there is a question of whether it is risky to promote as an anti-aging drug, given the lack of studies on such specific uses in extending life-span or delaying aging.

This is not an easy question to answer, there is also the possibility of any growth enhancement to accelerate the speed at which cancers grow, or to cause an increased risk of cancers themselves.

In this study by the Edison Biotechnology Institute on this particular topic a few semi-conclusions are drawn:

Identified mutations that DECREASE the tone of GH/IGF-1 have been associated with EXTENDED longevity in mice. In humans such corresponding or similar mutations have yet been identified, and if they do exist whether they affect longevity or not is not established. Remember mice data do not always transfer directly to human studies.

IGF-1 and GH have very different effects on glucose and lipid metabolism. GH blocks insulin action and promotes lipolysis and impedes lipogenesis, whereas IGF-1 has opposing effects.

After the age of 60 both IGF-1 and GH are at extremely low levels, this is known as somatopause.

Recombinant GH has potential antiaging properties, positive effects on body composition, BMD and skin thickness (GH is NOT IGF-1). GH has multiple side effects, such as carpal tunnel symptoms, increased risk of diabetes that makes it an unattractive option.

Decreased GH/IGF-1 Signalling has been linked to extended longevity in a wide variety of species, this does not mean that increase signaling necessarily decreases longevity. (but it is a possibility)

GH excess in mice has been linked to up to 30-40% shorter lifespan to wild-type mice). This is GH because the anti-insulin activity of GF leads to high insulin levels followed by insulin resistance, leading to damage of organs.

Treatments that normalized IGF-1 levels reduces the mortality rate of people who have Acromegaly (GH Excess in Humans)

FOXO proteins (longevity associated) are increased in expression, when there is an abscene of IGF-1 signalling. More research is needed on this, but supression of FOXO genes may mean reducing in stress resistance.

Increased GH and IGF-1 levels have been associated with the development of several types of cancers, such as breast and colon cancer, in mammals.

More studies are required for the use of HGH for anti-aging purposes, the consensus is that HGH is widely misused for anti-aging, there are benefits to body composition but potential risks as those raised in above points.

GH antagonists may be considered to slow aging (pegvisomant or somatostatin analogues). Though currently such agents are too expensive to be cost-effective for long periods of time. Importantly, the consequences of such agents are not established yet.

My conclusion of the study largely points towards "normalization" of IGF-1 levels is the most optimal use for IGF-1 therapy, too much or too little both causes problems. Though I would recommend reading the study itself to come to your own conclusions. IGF-1 appears to be under researched compared to HGH, and HGH has well documented problems when used over long periods of time making IGF-1 an interesting pathway to look at.

Comment Update

Rhonda Patrick's "Found My Fitness"

Comment Update

To test this, he and his colleagues added the gene for insulin-like growth
factor 1 (IGF-1), which stimulates satellite-cell activity in a test tube, to a
virus. They then injected the virus into one leg of young and old mice. Inside
the limb the virus entered muscle cells and produced the growth factor. After
several months the researchers looked at the muscles.
The untreated legs of old mice were 27 per cent weaker than those of young
mice, but the aged limbs that had received an IGF-1 boost regained their
youthful vigour. Even the muscles of the young mice had become stronger.